1. Field of the Invention
The present invention relates to a method for manufacturing a liquid discharge head used for a printer, a video printer, or the like serving as the output terminal for a copying machine, a facsimile equipment, a word processor, or a host computer, among some others. The invention also relates to a liquid discharge head manufactured by such method of manufacture, and a head cartridge, as well as to a liquid discharge recording apparatus. More particularly, the invention relates to a method for manufacturing a liquid discharge head provided with an elemental substrate having the electrothermal transducing elements formed thereon to generate thermal energy which is utilized for discharging liquid, a liquid discharge head manufactured by such method of manufacture, a head cartridge, and a liquid discharge recording head as well. In other words, the invention relates to a method for manufacturing a liquid discharge head which is used for recording by discharging ink or other recording liquid from the discharge ports (orifices) as flying droplets which adhere to a recording medium. The invention also relates to a liquid discharge head manufactured by such method of manufacture, and a head cartridge, as well as to a liquid discharge recording apparatus.
2. Related Background Art
There has been known the ink jet recording method, that is, the so-called bubble jet recording method, in which heat or some other energy is applied to ink to change the states thereof with abrupt voluminal changes to follow, and ink is discharged from each of the discharge ports by the acting force based upon this change of states of ink, and then, ink is caused to adhere to a recording medium for the image formation. Here, as disclosed in the specification of U.S. Pat. No. 4,723,129, the recording apparatus that uses this bubble jet recording method is generally provided with the discharge ports through which ink is discharged; the ink flow paths communicated with the discharge ports; and the electrothermal transducing elements serving as energy generating means for discharging ink.
In accordance with such method, it is possible to record images in high quality at high speed, and in a lesser amount of noises, and at the same time, it is possible to arrange the discharge ports for discharging ink in high density. Therefore, among many advantages, images can be formed in high resolution with a smaller apparatus, and also, color images can be also obtained as the excellent advantage of the method. In recent years, the bubble jet recording method has been widely utilized for a printer, a copying machine, a facsimile equipment, and many other office equipment. This method begins to be utilized even for a textile printing system and others for industrial use because of such advantages described above.
Meanwhile, along with the wider utilization of the bubble jet technologies and techniques for products in many fields, the various demands have been made more increasingly more in recent years as given below.
For example, the optimization of heat generating elements may be cited as the one that requires further studies on the enhancement of the energy efficiency, such as the adjustment of the thickness of the protection film provided for each of the heat generating elements. This technique is considered effective with respect to the improvement of the transfer efficiency of the generated heat to liquid.
Also, to obtain images in high quality, there has been proposed the driving condition that may implement the liquid discharge method which makes ink discharges at higher speeds with excellent ink discharges by the stable creation of bubbles. Also, from the viewpoint of the higher recording, there has been proposed an improved configuration of liquid flow paths for the provision of a liquid discharge head having the higher refilling speed of liquid to compensate for the amount of liquid that has been discharged.
Further, returning to the principle of liquid discharges, ardent studies have been made to provide a new liquid discharge method as disclosed in the specification of Japanese Patent Application Laid-Open No. 9-201966 and some others for the provision of heads and others by the utilization of bubbling, which has never been obtainable by the application of the conventional art.
Here, with reference to FIGS. 18A to 18D to FIG. 20, the description will be made of the conventional liquid discharge method disclosed in the specification of Japanese Patent Application Laid-Open No. 9-201966 and others, and also, of the head that uses such method. FIGS. 18A to 18D are views which illustrate the discharge principle of the conventional liquid discharge head. FIGS. 18A to 18D are cross-sectional view thereof, taken in the liquid flow path direction, respectively. Also, FIG. 19 is a partially broken perspective view which shows the liquid discharge head represented in FIGS. 18A to 18D. FIG. 20 is a cross-sectional view which shows the variational example of the liquid jet head represented in FIGS. 18A to 18D. The liquid discharge heads shown in FIGS. 18A to 18D and FIG. 20 represent the most fundamental structure for the provision of the enhanced discharge power and discharge efficiency by the control of the propagating direction of the pressure exerted by bubbling, as well as the direction of bubble development for the liquid discharges.
The terms xe2x80x9cupstreamxe2x80x9d and xe2x80x9cdownstreamxe2x80x9d used for the following description are related to the flow direction of liquid toward the discharge ports from the supply source of the liquid through the bubble generating areas, and these terms are also meant to indicate the structural direction thereof.
Also, the term xe2x80x9cdownstream sidexe2x80x9d related to the bubble itself means the discharge port side of the bubble that mainly acts directly upon the liquid droplet discharge. More specifically, with respect to the center of the bubble, this means the downstream side related to the aforesaid flow direction or the aforesaid structural direction or it means the bubble which is created on the area on the downstream side of the area center of the heat generating element. (Likewise, the term xe2x80x9cupstream sidexe2x80x9d related to the bubble itself means the upstream side in the aforesaid flow direction or the aforesaid structural direction with respect to the center of the bubble or this means the bubble created on the area on the upstream side of the area center of the heat generating element.)
Also, the term xe2x80x9ccomb teethxe2x80x9d is meant to indicate the configuration of a movable member where the front of its free end is released with the supporting point of the movable member being a common member.
For the liquid discharge head shown in FIGS. 18A to 18D, the heat generating element 102 that activates thermal energy on liquid as discharge energy generating element for discharge liquid is provided for the elemental substrate 101. On the elemental substrate 101, the liquid flow path 103 is arranged corresponding to the heat generating element 102. The liquid flow path 103 is communicated with the discharge port 104, and at the same time, communicated with the common liquid chamber 105 that supplies liquid to a plurality of liquid flow paths 103, which receives liquid in an amount equivalent to that of liquid having been discharged from the discharge port 104, respectively.
On the portion of the elemental substrate 101 that corresponds to the liquid flow path 103, the plate type movable member 106 is arranged in a cantilever fashion with its plane portion that faces the heat generating element 102. The movable member 106 is formed by an elastic metal material or the like. One end of the movable member 106 is fixed to the pedestal 107 formed by patterning the photosensitive resin on the walls of the liquid flow path 103 or on the elemental substrate 101. In this manner, the movable member 106 is supported by the pedestal 107 to constitute the fulcrum 108 of the movable member 106.
Also, with the movable member 106 formed to be the comb teeth shape, it becomes easier to produce the movable member 106 easily at lower costs. Also, the alignment of the movable member 106 can be easily made to the pedestal 107. The movable member 106 has its fulcrum 108 on the upstream side in a large flow from the common liquid chamber 105 to the discharge port 104 side through above the movable member 106 at the time of operating the liquid discharge. The movable member is arranged in a position to face the heat generating element 102 to cover the heat generating element 102 with a gap of approximately 15 xcexcm with the heat generating element 102 so that it has the free end 109 on the downstream side of the fulcrum 108. There is each of the bubble generating areas 110 between the heat generating element 102 and the movable member 106.
Now, with reference to FIGS. 18A to 18D, the description will be made of the operation of the liquid discharge head structured as described above.
At first, in FIG. 18A, ink is filled on the bubble generating area 110 and in the interior of the liquid flow path 103.
Then, in FIG. 18B, when the heat generating element 102 is energized, heat is applied to liquid on the bubble generating area 110 between the movable member 106 and the heat generating element 102. Then, bubble 111 is created in liquid on the basis of the film boiling phenomenon disclosed in the specification of U.S. Pat. No. 4,723,129 or the like. The pressure exerted by the creation of the bubble 111, and the bubble 111 act upon the bubble 111 priorly. Then, the movable member 106 is displaced so that it opens largely on the discharge port 104 side centering on the fulcrum 108 as shown in FIG. 18B, FIG. 18C or FIG. 19. By with the propagation of the pressure exerted by the bubble 111 by the displacement of the movable member 106 or by the displaced condition thereof or with the width provided for the leading end of the bubble 109, it becomes easier to lead the bubbling power of the bubble 111 to the discharge port 104 side. Thus, the fundamental enhancement can be attempted as to the discharge efficiency of the liquid droplets 132, the discharge power, the discharge speed, or the like. Here, in FIG. 19, a reference numeral 130 designates the area center of the heat generating element.
As described above, the technologies and techniques disclosed in the specification of Japanese Patent Application Laid-Open No. 9-201966 and others are those which control bubbles positively by changing the relationship between the fulcrum and free end of the movable member in the liquid path so that the free end of the movable member is positioned on the discharge port side, that is, on the downstream side, and also, by arranging the movable member to face the heat generating element or the bubble generating area.
Now, the liquid discharge head shown in FIG. 20 is also provided with the elemental substrate 201, the heat generating element 202, the liquid flow path 203, the discharge port 204, the common liquid chamber 205, and the bubble generating area 209, each structure of which is the same as each of those constituting the liquid discharge head described in conjunction with FIGS. 18A to 18D, respectively. Therefore, the detailed description thereof will be omitted.
For the movable member 206 formed in a cantilever fashion for the liquid discharge head shown in FIG. 20, a stepping portion is provided on one end at 206a. The movable member 206 is thus fixed onto the elemental substrate 201 directly. The movable member 206 is held on the elemental substrate 201. Then, the fulcrum 207 of the movable member 206 is formed with the free end 208 which is structured on the downstream side of the fulcrum 207.
As described above, with the provision of the pedestal for the fixing portion of the movable member or the stepping portion for the fixing portion of the movable member, the gap of approximately 1 to 20 xcexcm is formed between the movable member and the heat generating member so as to sufficiently produce effect by the movable member on the enhancement of the liquid discharge efficiency. Therefore, in accordance with the liquid discharge head or the like which is based on the discharge principle described above, it becomes possible to obtain the synergetic effect by the application of the bubbles thus created and the movable members which can displace by the creation of bubbles. Then, as compared with the discharge method and the liquid discharge head of the conventional bubble jet type which does not use any movable members, the liquid discharge efficiency is enhanced.
The main subject of the present invention is to provide the fundamental discharge characteristics of the liquid discharge method of the basic type, in which the conventional bubbles, particularly the bubbles which are created following the film boiling, are formed in the liquid flow paths, at a higher level which has never been expected in accordance with the conventional art.
The inventors hereof have ardently studied a new liquid discharge method that utilizes the bubbles which have never been obtainable by the conventional art in order to provide a head that uses such method. During the studies that the inventors have made, it has been attempted to carry out a first technical analysis on the principle of the mechanism for the movable member in the liquid flow path, beginning with the operation of the movable member in the liquid flow path; a second technical analysis beginning with the principle of the liquid discharge by the application of bubbles; and a third technical analysis beginning with the bubble generating area of the heat generating member for use of the bubble creation. Based on these analyses, the inventors hereof have established a completely new technology with which to control bubbles positively by making the positional relationship between the fulcrum and free end of the movable member so as to position the free end thereof on the discharge port side, that is, on the downstream side, and also, by arranging the movable member to face the heat generating element or the bubble generating area.
Then, in consideration of the energy generated by the bubble itself which exerts influences on the discharge amount, the inventors hereof have acquired the knowledge that the development component of the bubble on the downstream side is the largest factor that should be taken into account for the significant enhancement of the discharge characteristics. In other words, it has been found that the effective transformation of the development component of the bubble on the downstream side in the discharge direction is the one that may bring about the enhancement of the discharge efficiency, and discharge speed as well.
Further, it has been found that the structural elements should preferably be taken into account as to the heat generating area for the bubble formation, that is, the downstream side of the center line running through the area center of the electrothermal transducing element in the flow direction, for example, or the movable member and the liquid flow path which are related to the development of the bubble on the downstream side of the area center of the plane that may deal with bubbling, among some others.
Also, on the other hand, it has been found that the refilling speed can be enhanced significantly with the consideration given to the arrangement of the movable member, as well as to the structure of the liquid supply path.
Now, it is an object of the present invention to provide a method for manufacturing a liquid discharge head capable of manufacturing the highly reliable liquid discharge head whose discharge characteristics are stabilized when liquid is discharged by the utilization of the displacement of the free ends of the movable members by the pressure exerted by the creation of bubbles, and also, to provide the liquid discharge head which is manufactured by such method of manufacture, as well as the head cartridge and the liquid discharge recording apparatus. Also, it is another object of the invention to provide a method for manufacturing the liquid discharge head for which the movable members and others of the liquid discharge head can be formed in high precision and in high density. It is still another object of the invention to provide a method for manufacturing the liquid discharge head capable of performing high quality recording, and also, maintaining stabilized discharges without almost no changes in the flow resistance of the liquid flow paths, the close contactness between the elemental substrate and the flow path walls, and also, in the positions of the movable members and the liquid flow paths with respect to the heat generating elements even when the head temperature changes along the high speed printing or the like.
In order to achieve the objects discussed above, the method of the present invention for manufacturing a liquid discharge head, which is provided with a discharge port for discharging liquid; a liquid flow path communicated with the discharge port for supplying the liquid to the discharge port; a heat generating element arranged in the liquid flow path for creating a bubble in the liquid; an elemental substrate having the heat generating element therefor; and a movable member arranged for the elemental substrate having the free end thereof on the discharge port side with a gap with the elemental substrate in the position facing the heat generating element on the elemental substrate, the free end of the movable member being displaced on the discharge port side centering on the fulcrum structured near the supporting and fixing portion with the elemental substrate by the pressure exerted by the creation of the bubble for discharging the liquid from the discharge port, comprises the steps of: forming a gap formation member with Al to form the gap between the elemental substrate and the movable member on the surface of the elemental substrate on the heat generating element side; forming the material film for the formation of the movable member so as to cover the gap formation member; patterning the material film by dry etching; and forming the gap by eluting the gap formation member. Here, the gap formation member formed with Al is extended to be the etching area of the material film in this method of manufacture.
In order to achiever the objects discussed above, the method of the present invention for manufacturing a liquid discharge head, which is provided with discharge port for discharging liquid; a liquid flow path communicated with the discharge port for supplying the liquid to the discharge port; a heat generating element arranged in the liquid flow path for creating bubble in the liquid; an elemental substrate having the heat generating element therefor; and a movable member arranged for the elemental substrate having the free end thereof on the discharge port side with a gap with the elemental substrate in the position facing the heat generating element on the elemental substrate, the free end of the movable member being displaced on the discharge port side centering on the fulcrum structured near the supporting and fixing portion with the elemental substrate by the pressure exerted by the creation of the bubble for discharging the liquid from the discharge port, comprises the steps of forming a gap formation member with Al to form the gap between the elemental substrate and the movable member on the surface of the elemental substrate on the heat generating element side; forming the material film for the formation of the movable member so as to cover the gap formation member; pattering the material film by dry etching; and forming the gap by eluting the gap formation member. Here, the gap formation member formed with Al is extended to the etching area of the material film in this method of manufacture.
Also, a method of the present invention method for manufacturing a liquid discharge head, which is provided with a discharge port for discharging liquid; a liquid flow path communicated with the discharge port for supplying the liquid to the discharge port; an elemental substrate having a heat generating element provided for one face side thereof for creating bubble in the liquid in the liquid flow path; a liquid flow path side wall formed on the elemental substrate to form the liquid flow path; and a movable member arranged for the elemental substrate, having the free end on the discharge port side with a gap with the elemental substrate in the position facing the heat generating element on the elemental substrate, and then, the free end of the movable member being displaced on the discharge port side centering on the fulcrum structured near the supporting and fixing portion with the elemental substrate by the pressure exerted by the creation of the bubble for discharging the liquid from the discharge port, comprises the steps of forming a gap formation member locally for the formation of the gap between the elemental substrate and the movable member on the surface of the elemental substrate on the heat generating element side; forming the silicon material film for the formation of the movable member on the surface of the elemental substrate on the heat generating element side; forming a first mask layer on the surface portion of the material film for the formation of the movable member corresponding to the movable member; forming the silicon material film for the formation of the flow path side wall on the surface of the material film for the formation of the movable member and the surface of the first mask layer; forming a second mask layer on the surface portion of the film for the formation of the flow path side wall; forming at least a part of the liquid flow path and the flow path side wall by patterning the material film for the formation of movable member and the film for the formation of the flow path side wall by etching using the first and second masks, and removing the gap formation member and the second mask layer to form the movable member.
Also, a method of the present invention for manufacturing a liquid discharge head, which is provided with a discharge port for discharging liquid; a liquid flow path communicated with the discharge port for supplying the liquid to the discharge port; an elemental substrate having a heat generating element provided for one face side thereof for creating bubble in the liquid in the liquid flow path; a liquid flow path side wall formed on the elemental substrate to form the liquid flow path; and a movable member arranged for the elemental substrate, having a free end thereof on the discharge port side with a gap with the elemental substrate in the position facing the heat generating element on the elemental substrate, and a stopper portion to regulate the displacement of the movable member, the free end of the movable member being displaced on the discharge port side centering on the fulcrum structured near the supporting and fixing portion with the elemental substrate by the pressure exerted by the creation of the bubble for discharging the liquid form the discharge port, comprises the steps of arranging the film for the formation of flow path side wall on the movable member on the elemental substrate; and embedding part of liquid flow path and the stopper portion simultaneously on the movable member by etching the film using the pattern different from the liquid flow path pattern in the movable area of the movable member.
In accordance with the methods of manufacture of the present invention described above, it becomes possible to manufacture the liquid discharge head which is capable of directing the exerted pressure toward the discharge ports with the provision of the movable members for the liquid discharge head, which are displaced by the pressure exerted by the creation of bubbles, and also, capable of discharging liquid by the application of high discharge pressure with high discharge energy efficiency, while enhancing the capability of refilling discharge liquid.
Also, silicon is used for the elemental substrate. Then, using silicon material, such as silicon nitride, silicon oxide, or silicon carbide, as the material for the formation of the movable members and the flow path side walls, the thermal expansion coefficients of these members become almost equal. Thus, it becomes possible to prevent strength from becoming weaker for the fixing portion of the movable members with the elemental substrate, as well as for the close contactness between the flow path side walls and the elemental substrate. As a result, it is possible to manufacture the liquid discharge head for which almost no changes are made in the close contactness between the elemental substrate and flow path walls, the positions of the movable members and flow path walls, and also, in the flow resistance of liquid flow paths even when the temperature of the liquid discharge head is caused to change.
Further, the cavitation proof film provided for the elemental substrate is grounded when forming the material film for the formation of movable members and the film for the formation of flow path side walls by use of the plasma CVD method. As a result, it becomes possible to prevent the heat generating elements and other functional elements on the elemental substrate due to the ion seed and radical decomposed by the plasma discharges.
Further, the gap formation members are grounded when forming at least a part of the liquid flow paths and flow path side walls by patterning the material film for the formation of the movable members and the film for the formation of the flow path side walls by use of the dry etching. It becomes possible to prevent damages that may be caused to the heat generating elements 2 and other functional elements on the elemental substrate 1 due to the ion seed and radical loads generated by the decomposition of CF4 gas or other gas, for example.
Also, the liquid discharge head of the present invention is the one that discharges liquid by the utilization of bubbles created when thermal energy is activated on liquid, which is manufactured by the method for manufacturing a liquid discharge head described above.
Further, the head cartridge of the present invention is provided with the liquid discharge head manufactured by the method of manufacture described above, and also, provided with the liquid container that contains liquid to be supplied to this liquid discharge head.
Further, the liquid discharge recording apparatus of the present invention is provided with the liquid discharge head manufactured by the method of manufacture described above, and also, provided with means for supplying driving signals to supply them for discharging liquid from the liquid discharge head.
Further, the liquid discharge recording apparatus of the present invention is provided with the liquid discharge head manufactured by the method of manufacture described above, and also, provided with means for carrying a recording medium to carry the recording medium that receives liquid discharged from the liquid discharge head.
The liquid discharge recording apparatus described above performs recording by discharging liquid from the aforesaid liquid discharge head for the adhesion of the liquid to the recording medium.
The terms xe2x80x9cupstreamxe2x80x9d and xe2x80x9cdownstreamxe2x80x9d used for the description of the present invention are related to the flow direction of liquid toward the discharge ports from the supply source of the liquid through the bubble generating areas (or movable members), and these terms are also meant to indicate the structural direction thereof.
Also, the term xe2x80x9cdownstream sidexe2x80x9d related to the bubble itself means the downstream side of the center of a bubble in the aforesaid flow direction and the aforesaid structural direction or this term means the bubble created on the downstream side area of the area center of a heat generating element. Likewise, the term xe2x80x9cupstream sidexe2x80x9d related to the bubble itself means the upstream side of the center of a bubble in the aforesaid flow direction and the aforesaid structural direction or it means a bubble created on the upstream side area of the area center of a heat generating element.
Other objectives and advantages besides those discussed above will be apparent to those skilled in the art from the description of a preferred embodiment of the invention which follows. In the description, reference is made to accompanying drawings, which form a part hereof, and which illustrate an example of the invention. Such example, however, is not exhaustive of the various embodiments of the invention, and therefore reference is made to the claims which follow the description for determining the scope of the invention.